So far we've seen Unix tools that will let you find, translate, and replace.…The next useful Unix tool I want to introduce you to is cut.…Cut allows you to cut out selected portions of each line of a file.…We could probably write a sed command that would do something similar to what…cut does, but cut is much simpler and easier to use.…The first thing you need to know about cut is that it can cut three things,…characters, bytes, or fields, and we are always going to need to pick one of those.…We are only going to be looking at characters and fields, and the reason why is…that bytes in English is going to be exactly equivalent to characters,…because every character takes up exactly 1 byte.…

And really, bytes are there mostly for when you are thinking about raw data,…not actual characters, but raw data, and you want to grab a certain amount of bytes out of it.…We're working with text files here, so we're really thinking about characters,…and most times that's what you will be doing.…So characters and fields is where we're going to focus.…

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Released

4/29/2011

Unix for Mac OS X Users unlocks the powerful capabilities of Unix that underlie Mac OS X, teaching how to use command-line syntax to perform common tasks such as file management, data entry, and text manipulation. The course teaches Unix from the ground up, starting with the basics of the command line and graduating to powerful, advanced tools like grep, sed, and xargs. The course shows how to enter commands in Terminal to create, move, copy, and delete files and folders; change file ownership and permissions; view and stop command and application processes; find and edit data within files; and use command-line shortcuts to speed up workflow. Exercise files accompany the course.

Topics include:

Moving around the file system

Creating and reading files

Copying, moving, renaming, and deleting files and directories

Creating hard links and symbolic links

Understanding user identity, file ownership, and sudo

Setting file permissions with alpha and octal notation

Changing the PATH variable

Using the command history

Directing input and output

Configuring the Unix working environment

Searching and replacing using grep and regular expressions

Manipulating text with tr, sed, and cut

Integrating with the Finder, Spotlight, and AppleScript

Skill Level Beginner

6h 35m

Duration

2,053,799

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Q: The exercise files for the following movies appear to be broken:
07_02_files
07_03_files
07_04_files
07_05_files
08_03_files

Is there something wrong with them?

These exercises include one or more "dot files", whose file names start with a period. These files are normally hidden from view by the Finder. So that they would show up in the Finder, the period has been removed from the file names. Additionally, "_example" has been added at the end of the file name to make it clear that the file will not work as-is.
To make the dot files usable, either:

1) Open the file in a text editor to view its contents. Note that it may not be possible to double-click the file to open it because there is no file extension (such as .txt).
2) Resave the file under a new name (usually by choosing File > Save As), adding a "." to the beginning of the file name and removing "_example" from the end.

OR

1) Copy and rename the file from the Unix command line using the techniques discussed in this course. Rename the file by adding a "." to the start and removing "_example" from the end. Include the "-i" option to prevent overwriting an existing file unexpectedly.
Example: cp -i ~/Desktop/Exercise\ Files/Chapter_07/07_02_files/bashrc_example ~/.bashrc

The instructor uses the UNIX program 'units' to convert 72° Fahrenheit to degrees Celsius. The returned value of 40 is incorrect. The correct result should be 22°C. What's the reason for this discrepancy?

The problem is that units does the 5/9 calculation but does not have the ability to subtract 32. So you'll need to subtract (or add) the 32 degrees yourself.